Dimension averaging measuring instrument



May 4, l954 G. E. soRENsEN 2,677,186

DIMENSIN AVERAGING MESURING INSTRUMENT 3 Sheets-Sheet l Filed Jan. 311950 May 4, 1954 G. E. soRENsEN 2,677,186

DIMENSION AVERAGING MEASURING INSTRUMENT Filed Jan. s1. 195o ssheds-sheet 2 1p fra BE Fol/vaag 13 bnr se' ful/N111 26 i INVENTOR StgeATTORNEY May 4, 1954 G. E. soRENsl-:N

DIMENSION AVERAGING MESURING INSTRUMENT 3 Sheets-Sheet 3 Filed Jan. 311950 A@ .ma y@ INVENTCR ATTGRNEY pering instruments Patented May 4, 1954DIMENSION nysRAGING-MEASUMNG INSTRUMENT George E. Sorensen, Fairfield,Conn. Application January 31. 1950, Serial No. 141,448

V13 Claims. l

This invention relates to work sensing or caliafiording direct readingof the true measure of distance between two unmarked loci, such as theunmarked centers of two eccentrically related circles or round holesandwithout knowing or having to ascertain the sizes of the holes.Diametrically opposite edges of one such hole may be termed a first pairo1' discernible marks between which lies one of the hole centers orunmarked loci, while diametrically opposite edges of the other hole maybe termed a second pair of discernible marks between which the otherhole center or unmarked locus lies.

It is a general purpose of the invention to provide a caliperinginstrument which will produce a direct reading of the true centerspacing or distance between such hole centers or unmarked loci withoutresort to mental computation and as a result of merely caliperingsuccessively certain distances between the aforesaid discernible marks.For instance, the calipers may be set to span the distance between thenearest together hole edges and as a separate operation set to span thedistance between the farthest apart hole edges. This latter distancewill overlap and be inclusive or -the irst said distance. When these twosteps have been performed and because of the overlapping of the twodistances referred to, what has actually been-calipered is the sum ofthediameters of the two holes plus twice the distance, if any, thatseparates the two holes. In order to register a direct reading of thetrue center spacing of thetwo holes thefinstrument is calibrated toregister one half the total distances `that are actually oalipered bythe instrument. `In the example referred to, the instrument willregisterthe sum of the radii of the two holes plus the distance, if any,`bywhich the holes are-separated, this sum beingthe ofthe center spacing ofthe holes. Such sum is also `the average of the distance between thenearest together hole edges and the distance between the farthest aparthole edges.

The present improvements involve simplification in the number andcomplexity of parts and in the number of manipulative operationsrequired by certain instruments for a comparable purpose disclosed in mycopending application, Serial No. 28,368, vfiled May 2l, i948. The useofthose instruments necessitated an extraneous step of mechanicallycorrecting the registering'of a false dimensional magnitude additionalto two successive calipering operations before the instrument couldultimately be made to register a Jdirect reading of the true distancebetween the unmarked loci or hole centers.

In this class of measuring instruments I prefer to-provide ais'cale ofnumerical `characters denoting 'progressive dimensionalVV magnitudesthat desired direct reading are fractional proportions of the trueaccumulative measure o the spacings between the characters. For example,a scale marked with a series of graduations progressing away from thebeginning, or zero end, oi' the scale and which are actually 1/4" apartmay be labelled by characters denoting that they are 1/3" apart so thata character denoting a graduation mark fourth in order away from "zerowill be designated by the fractional magnitude 1/2" instead of by thetrue magnitude l". An instrument equipped with such a scale will givedirect readings which may be one half the sum of the actual magnitudesof two work dimensions that are successively calipered in an additivemanner by the instrument. or in other words, the average of the numberof work dimensions so calipered. Thus if the diameter of a circle o-rround hole is calipered by an instrument having such a half magnitudescale of characters, the resultant dimensional reading on the instrumentwill be the radius of the hole. Ii the added lengths of the diameters oftwo tangent circles or round holes are measured by a single overallcalipering operation the instrument will read a value equal, not to thesum of the diameters of the two holes, but a value equal to the sum ofthe radii of the holes, such sum obviously being the true distancebetween the centers of the holes. However, when center distance betweentwo eccentric holes that are spaced apart by some distance is to beascertained, an instrument of the subject kind cannot be made to readthe true distance between the hole centers by means of only a singlecalipering operation.

It is an object of this invention to enable the true distance betweenthe centers of two eccentric spaced apart holes to be read directly onthe instrument as a result of only two successive work calipering steps,eliminating all need for correction of false registration that wouldinvolve an extraneous adjustive step in manipulating the instrumentadditional to two simple work calipering operations.

A further object of the present improvements is to provide an instrumentthat can give a direct reading of the average magnitude of any two ormore overlapping distances by merely calipering such distancessuccessively.

A specific object of the invention is to ascertain by direct reading ona measuring instrument and without mental computation the true distancebetween centers of two eccentric holes by merely calipering successivelythe distance between the nearest together edges of the two holes and thedistance between the farthest apart edges of the two holes whether suchholes are tangent or are separated by a space.

The foregoing and other advantageous uses of the present improvementswill `become clear in 1greater particular from thefollowing description3 oi' a successful embodiment of the invention, which description hasreference to the appended drawings wherein:

Figs. 1 and 2 both illustrate similar pairs ci spaced eccentric coplanarcircles of illustrative dimensions that may be scribed on any flat worksurface and whose center spacing is ascertainable by direct reading onmy improved instrument even if the circle centers are unmarked loci onthe work.

Figs. 3 `to 6, inclusive, show successive steps in maneuvering one formof my improved instrument to produce a direct reading thereon of thedistance between centers of the two circles of Fig. 1 without sensingsuch centers.

Figs. 7 to l1, inclusive, show a diierent series of successive steps inmaneuvering a modied form of the instrument in a manner to arrive at thesame direct reading of center distance as in Fig. 6.

Figs. 12 and 13 both illustrate similar pairs of spaced eccentric roundholes, of the same dimensions as the mere circles of Figs. l and 2,located side by side in a solid work block and whose center spacing canbe ascertained with great precision by use of the still further modifiedforms of my improved instrument shown in Figs. 14 to 22, inclusive.

Figs. 14 to 17, inclusive, show successive steps of maneuvering themodified form of instrument shown in Fig. 14 so as to caliper the edgesof the holes of Figs. 12 and 13.

Figs. 18 to 22, inclusive, show a diierent series of steps inmaneuvering a modification of the instrument in Fig. 18 in a manner toarrive at a direct reading of center distance like that in Fig. 17.

Fig. 23 shows a manner of handling the instrument of Figs. 14 to 1'7,inclusive, making it*H unnecessary to grasp or use as a handle the beamthat carries the readable scale of graduations and indicia characters.

Fig. 24 is an enlarged fragmentary plan View of the instrument of Fig.23.

Fig. 25 is an endwise view of the instrument looking from the righttoward Fig. 24.

Fig. 26 is a fragmentary View taken in section on the plane 23-26 inFig. 25 showing a conventional detail of construction of spring gib forapplying the jaw locking pressure of the thumb screw against the beamedge.

Fig. 27 is a perspective view showing in suitable actual size reinementsin preferred construction of an instrument embodying the inventionadvantageous for use in any of the manners herein disclosed with respectto diagrammatic Figs. i to 22, inclusive.

Fig. 28 is a fragmentary face view of the instrument in Fig. 27 insuitable actual size showing some of the parts in section on the plane23-28 in Fig. 29, looking in the direction of the arrows.

Fig. 29 is an edgewise plan view of the instrument in Fig. 28.

Fig. 30 is an endwise View looking from the left at Fig. 29.

Fig, 31 is a view taken in section on the pla-nes 3I-3I in Fig. 28looking in the direction of they arrows.

Fig. 32 is a bottom plan view drawn on an enlarged scale looking upwardat the ends of the calipering legs in Fig. 28.

In describing a successful embodiment of the present improvements themethod of using the improved instrument is illustrated diagrammaticallyin four series of drawing gures. In Figs. 1 to 11, inclusive, there arerepresented progressive steps in the setting of two diiiering forms ofthe instrument suitable for ascertaining the center spacing of eccentriccircles W, w merely scribed on paper or on a metal surface. Here themovable instrument jaws I0, I l carry work sensing terminal portions orlegs I2 and I3 whose work contacting terminals are sharp points thatcoincide theoretically when the instrument parts are positioned as inFig. 3. Figs. 12 to 22 illustrate corresponding steps in the setting ofmodiiied forms of the instrument suitable or ascertaining center spacingof spaced apart holes located side by side in a work block i3 and wherethe relatively movable instrument jaws 20, 2| carry legs 22. 23 capableof calipering the edges of the holes by abutting contact therewith, Legs22, 23 possess width in their terminal portions preventing at least twoof their work sensing terminals 26, 2l from coinciding in Fig. 14. Twoothers of the work sensing -terminals 24, 25 of legs 22, 23 are able tocoincide theoretically in the starting condition of the instrument shownin Fig. 14. In accordance with conventional practice in an instrumentintended for calipering round holes, each terminal 24, 25, 26 and 21 isof more abrupt rounded ciuvature than the circumference of a circlehaving a diameter equal to the distance between terminals 26 and 21.

The median of width of the leg, as the term median is herein used, is areference point 4l, 43, 6l or 68 on each leg which may or may not bevisibly marked thereon and which in case of the spaced apart worksensing terminals 24, 26 or 25, 2l in Figs. 12-22 or in case of the worksensing terminals 14, 8E or 15, 8l in Figs. 27-32 is located midwaybetween such work sensing terminals on each leg or terminal portion ofthe jaw. But in Figs. 1-11, the calipering legs I2, I3 possess singlepointed ends which serve as their work sensing terminals. Hencetheoretically such terminals possess no width wherefore the singlepointed end of each of legs I2, I3 constitutes the reference point abovereferred to and that sometimes herein is called a median of width."

Mechanical construction of an instrument capable of use asdiagrammatically indicated in Figs. 14 to 17, inclusive, is illustratedin Figs. 24, 25 and 26 of the drawings. It includes a blank jaw 20 andan indexed jaw 2|, the latter carrying the index mark 29. Both of thesejaws are slidably engaged with a rigid beam 34 which confines them torectilinear relative movement for measuring work. Fig. 26 shows indetail a spring gib 33 of conventional construction which transmits thelocking pressure of the thumb screw to the bea-m edge. Beam 34 carries ascale 45 of equally spaced characters 36 which in the form shown arenumerals respectively denoting fractional magnitudes of the actualdistances of the characters from the beginning or zero end of the scale.In other words, the range of the scale begins theoretically with a. zeromark at location 31 and the characters 33 progress serially away fromthis beginning of the scale. However, the numerical characters used todesignate the graduations 38 denote dimensional magnitudes which areonly one half the respective actual distances or true aggregates ofspacings of the graduations from the beginning of the scale. Thus thegraduation mark which is fourth in order away from zero location, andactually f. spaced V2" awa-y from zero, is denominated by the numericalcharacter 1A. Thus the instrument will give readings of distance onscale 45 which are only one half the true magnitudes of the caliperingdisplacement from each other of jaws 2l) and 2| along the scale.

For the particular purposes oi.' this invention, beam 39 is providedwith an enlarged at head 39 having at least one surface roughened toserve as a handle for grasping the beam. Head 39 presents a shoulder 49in xed relation to said scale which shoulder is abuttlngly engageable bythe jaw thereby to limit movement of both jaws 29 and 2l relative tobeam 34 in one direction at a location which brings index 29 intoregister with a predetermined graduation on scale 45. Thereby ispredetermined a constant or initial starting relationship of the jaws toeach other and to the scale 45 accompanied by a constantly correspondinginitial registration of the indicators 29 and 45 before the jaws aredisplaced to perform a measuring function. Shoulder 40 thus servesmechanically as a stop which, of course, may take other forms.

The elemental form of instrument diagrammatically shown in Figs. 2 to1l, inclusive, is constructed as above described with the exception thatthe jaws ID and I I carry pointers I2 and I3 which are capable of beingclosed together thus to eliminate the initial spacing apart of terminals26 and 21.

Because it is simpler to understand some of the principles of operationby consideration of the instrument of Figs. 1 to (i, it will be assumedthat (W) and (w) are two eccentric circles scribed on a piece of paperor flat metal surface and separated by a space (S) equal to 1".Diametrically opposite points on circle (W) are designated (F) and (N)respectively. They constitute one pair of discernible marks betweenwhich there lies a-n unknown locus, or center (C) of circle (W).Diametrically opposite points on circle (w) are designated respectively(n) and (i). These constitute a second pair of discernible marks betweenwhich lies the unmarked locus or center (c) of the circle (w). It is thefunction of my improved instrument to register for direct reading theactual center spacings or distances between centers (C) and (c) withoutresorting to mental computation and as a result of merely caliperingsuccessively the distance between points (N) (n) and the points (F) (f).The following description makes clear how this is accomplished by thenovel provision and relationship of beam head 39 to the location of therange of scale 35, such relationship permitting the blank jaw I9 tointervene between the beam head 39 and the indexed jaw II so that index29 will register with the zero" graduation on the scale in the startingposition of parts shown in Fig. 3.

In Fig. 3 the work sensing points or tips of caliperng legs I2, I3 onjaws I0, II, herein also referred to as "reference points or medians ofwidth of the work sensing portions of such jaws are closed together andthe thumb screw of blank jaw I9 is tightened and locks that jaw to thebeam M while thumb screw 3| of jaw II remains loose to enable the latterjaw to be slidable along beam MI for measuring operations. In Fig. 4 forthe purpose of sensing the distance (S), jaw l I has been displaced fromjaw I0 a distance equal to one inch which results from placing the Worksensing pointers I2 and I3 on the nearest together points (N, n) ofcircles (W, w) respectively. This causes the index 29 to register withthe graduation mark of character 1/2 on the beam scale 35. Here thethumb screw 3l of jaw I I is tightened and the thumb screw 3D of jaw II)is made loose. Loose jaw I0 is then advanced toward the right intoabutting contact with tight jaw II after which thumb screw 3i) is madetight and thumb screw 3| is loosened again. This locks the blank jaw Ii)on the beam at a displacement of l from its initial position against thebeam head 39.

The indexed jaw l I is now again displaced from the locked blank jaw I0an extent determined by placing the points of legs I2 and I3respectively on the farthest apart point (F, f) of the circles (W, w).This second displacement of jaw Il from jaw I9 includes an increment ofmovement that is a repetition of the initial amount of movement 1" ofjaw II toward the right in Fig. 4. In other words this repeateddisplacement (1) of jaw II has been added to a further displacement ofjaw Il which equals the sum of the diameters of circles (W) and (w) sothat jaw II has now been displaced from its initial or starting positionin Fig. 3 to the extent of (D) plus (2S) plus (d), or a total distanceof 31/2". This results in a scale reading given by the registration ofindex 29 with the scale character 1%". This is a direct reading of thetrue distance between the unmarked centers (C, c) ofthe circles (W, w)which have never been directly sensed by the points of legs I2 and I3.

In Fig. 7 the work sensing points I2, I3 are closed together as in Fig.3, but here the index mark 2s is carried on the jaw Ill' instead of onthe jaw I I', and the location of the range of scale 35 has beenmodified in relation to the head 39 of beam 418 so that index 29' on jawlil' can now register with the beginning or zero graduation of the scalewhen the parts are in their initial or starting position shown in Fig.7. Here, as in Fig. 3, thumb screw 39 may be tight and the thumb screw3l loose. As a rst step in a differing series of instrument maneuveringwork measuring operations the jaw II may be displaced a distance equalto (D) plus (S) plus (d), or 21,-/2". At this point thumb screw SI willbe tightened and thumb screw 3D loosened so that indexed jaw III' may bemoved toward the right into abutting contact with the now tight blankjaw I I as shown in Fig. 9. Index 29 is thus brought into register withthe character 1%". Now thumb screw 39 is tightened and thumb screw 3Iloosened so that jaw II' can again be displaced from jaw III to anextent determined by placing the points of legs I2 and I3 in sensingcontact with the circle points (N) and (u). This adds into theinstrument a second occurrence of the distance, (S) equals 1". Thus whenloose indexed jaw I9' is again brought into engagement with the tightblank jaw Il', the index mark 29 as shown in Fig. 1l will be broughtinto register with the scale character 1%" as in Fig. 6, this being thetrue spacing of the unmarked circle centers (C, c). Either (DD-(n) or(F)(f) may be sensed first.

The calipering form of instrument diagrammatically shown in Figs. l2 to22, inclusive, is operated like the elemental form of instrument ofFigs. 3 to 11 except that the presence in the legs 22, 23 of that widthwhich separates the work sensing terminals 2S, 21 necessitates adifferently placed relationship of the range of scale 45 to the beamhead or stop 39 so that index 29 shall register initially not with zero"graduation on the scale but with the graduation labelled 1/4", thisdimension being half the distance between work sensing terminals 26, 21or in other words that distance indicated by the space between scratchmarks 41, `4B diagrammatically represented on the legs 22, 23,respectively, each of which scratch marks is at the median of the widthof its respective leg. Such median corresponds to the actual worksensing points of legs |2 and |3 in Figs. 1 to 11. Any separation of thelegs 22, 23 will be reected by a correspondingly increased separation ofthe scratch marks or medians 41, 48, but due to the fact that there isan initial separation of 1/4" between them the index 29 initiallyregisters that dimension on the scale. This constant of 1A" will thusautomatically be incorporated in all subsequent readings pointed to bythe index 29 resulting from progressive movements of jaw 2| along thescale. Thus if the work sensing terminals rst be separated to the extentof the distance (S) or l as in Fig. l5, as would occur by calipering thenearest together edges of holes (W) (w) by contact therewith of legterminals 24, 25, this will leave the scratch marks 41, 48 a distanceapart of 11/4" which is equal to said l" movement plus their initialspacing of 1A". The corresponding registration of index 25) becomes 1%",this being the sum of 1/2", or half separation movement of the jaws,plus the constant V4 of initial separation of scratch marks 41, IIB.Thus the scale graduation marked 3A" may appropriately be termed thebeginning graduation in this particular form of the invention. Now thumbscrew 31| will be tightened and thumb screw 3|) loosened to permitbringing loose jaw into abutting contact with tight jaw 2|, after whichthumb screw 3G is tightened and thumb screw 3| is loosened. Now when thejaw 2| is next separated from jaw 2li into calipering contact with thefarthest apart edges (F) (f) of holes (W) (w) as shown in Fig. 23, thescratch marks d1, A8 will not have had their spacing increased by anamount as great as the distance between (F) and (f). Their spacing willfall short of such actual distance to the extent of the 1/4" constantinitial separation heretofore referred to which is one half the combinedwidth of legs 22, 23 at their work sensing terminal portions. Theresultant reading of the index 29 becomes 1%" as is the case in Fig. 6,this being the true distance between the unmarked centers of the holes.

In Figs. 18 to 22, the relation of the range of scale 46 to the beamhead 39 is again changed in accordance with the carrying of index 29 onjaw 20' instead of on the jaw 2|. In accordance with the manner ofmanipulation represented in Figs. 7 to 1l, the instrument of Figs. 18 to22 may first have its jaws spread as in Fig. 19 so that its sensingterminals 26, 21 caliper the hole edges (F) and (f). The thumb screw 3|may now be tightened while thumb screw 30 is made loose to permit ofbringing indexed jaw 20 up into contact again with blank jaw 2|'. Thenthumb screw 3|) will be tightened and thumb screw 3| loosened, afterwhich the terminals 24, 25 are set to caliper the hole edges (N) and(n). When indexed jaw 20 is last brought up into contact with blank jaw2|', index 29' will be found to read 1%" on the scale as in Fig. 22indicating directly and truly the center distance of holes (W) (w).

From the described various manners of operating several forms of theimproved instrument, it will be realized that the function of theinstrument broadly is to space o additively on the scale of the beam bymeans of the slidable jaws accumulative distances equal to dimensions ofwork successively measured by the instrument and to indicate the averagevalue of said dimensions by the direct reading of the instrument, thusregistering the radial dimensions rather than the actually senseddiametrical dimensions of the circles, and registering a singleoccurrence of the space (S) between the holes rather than the actualdouble occurrence which becomes set up in the instrument. In the usesherein illustrated there are but two work dimensions successivelymeasured, these being in one case the work dimension (S) and in theother case the work dimension (D) plus (S) plus (d). The accumulateddistance spaced oi on the scale equals (D) plus (2S) plus (d). The scalereads one half this accumulative distance. or (1/2D) plus (S) plus(l/zd) which is the center distance between the work circles or theholes. In other kinds of work measurement it might be desired toaccumulate mechanically on the scale the sum of three or more successivemeasurements of work dimensions. To cause the scale to give a directreading of the average of three distances the graduations of the scalewill be marked by numerals which denote one third instead of one halfthe actual distances of the graduations from the beginning of the scale.If four work dimensions are to be successively measured and accumulatedon the scale, the graduation characters will denote one quarter of theactual distance of the graduation from the beginning of the scale inorder to produce a direct reading of the average of all fourmeasurements that have been accumulated on the scale, etc.

The instrument of Figs. 27 to 32 which embodies the invention isidentified in its correspondingly operative parts with the instrumentsof Figs. 14 to 17 and Figs. 24 to 26 by use in genera1 of referencenumerals having corresponding final digits and incorporates refinementsof particular advantage in practical shop use. The beam 54 carries thescale of graduations 55 designated by the numerical characters 56.

Slidable on beam 54 are two jaws 51, 58 comparable to jaws 20 and 2| inFig. 14, either of which jaws may be marked as the indexed jaw if thelocation of the range of scale 5E is suitably related to the beam stop8l) as herein taught. In Figs. 27 to 32, 58 designates the indexed jawhaving the index mark 59, and 51 designates the other or blank jaw.

The spring gib 53 and the thumb screw 6| in each of these jaws may beregarded as conventional while the calipering legs 62 and 63 mayadvantageously have the shapes indicated in the drawings and may containcentrally in the end of each leg a threaded hole G4 for insertedmounting therein of spacing-off work-sensing pointer terminalscomparable to I2 and I3 in Figs. 3 to l1. When such pointers areinstalled centrally in the end of each leg the work sensing terminalpointers may coincide with the vertical reference lines 61, 63 which arecomparable to the scratch lines 41, 48 in Figs. 14 to 22.

As differing from the construction of the instrument diagrammed in Figs.14 to 22, the nearest together work sensing terminals 14 and 15 on legs62 and 63, respectively, which are comparable to Work sensing terminals24 and 25 in Figs. 14 to 22, are prevented from ever coming directlyinto contact with each other by the mutually abutting hardened steelprojecting stop studs 16 and 11 xed on jaws 51 and 58, respectively. Asimilar stop stud 18 is fixed on the opposite or left side of jaw 51 andprojects from the latter for abutment against a stop finger B0. Thisringer may constitute an integral extension of the metal of beam 54 butis herein shown as a separate part iixedly secured against the face ofthe beam by screws 8l. The mutually contacting end surfaces of stopstuds 'I6 and 11, and of stop stud i3 with the stop finger 30, affordeasily cleaned areas of minimum size which are so placed as to exertwith strongest effect their resistance to strains and shocks of impactoccasioned by sliding either jaw into bumping contact with the other jawor with the stop iinger 80. They mutually contact at a most effectivepoint to prevent torque forces tending to make the jaws tilt relativelyto each other or relatively to the beam 54 and thus prevent inaccuraciesfrom creeping into the relationship of the actual spacings of the worksensing terminals 14, 'l5 and the corresponding registration of index 59with the proper graduation on. the beam scale 55.

Legs 62 and 33 possess, in addition to their inner work sensingterminals 14 and 15, outer Work sensing terminals B6 and 81,respectively. Since the aforesaid reference line 6l is midway betweenthe work sensing terminals 'I4 and 86 and the reference line 6B ismidway between the work sensing terminals 15 and 8l, lines 61 and 6Bcannot approach any closer to each other than the minimum spacing of it"represented in Fig. 28. The index 55, therefore, needs to be initiallyin register with a scale graduation of different value than is the casein Fig. 14. In other words, the constant to be initially registered bythe index 59, instead of being merely one half the combined widths oflegs 62, 63, becomes said half width of the legs plus the ris" by whichterminals 14, l5 are initially spaced apart. Such constant in aninstrument of the dimensions indicated in the drawingsv will be 1/2"plus s" or lf3". It will be noted that this still is the disstance thatseparates the leg centers 61 and 68 in their nearest togetherrelationship. Thus the location of the range of scale 55 in Figs. 27 and28 will be so changed that index 59 registers initially with thebeginning graduation denoting l" on the scale.

The instrument of Figs. 2'? to 32 may be used in any of the waysexplained diagrammatically in Figs. 1 to 23, and in many other wayswhich the user will find convenient for mechanically determining theaverage values of plural measurements or of. predetermined fractionalparts of such plural measurements by sensing or calipering suchmeasurements successively in any of the manners hereinbefore described.

While circles and round holes have been illustrated as the work to bemeasured. all forms of the instrument herein disclosed are fully capableof calipering and indicating the corresponding center distances betweenother kinds of work shapes such as by calipering the side surfaces orshoulders of spaced apart projections to indicate the distance betweenthe unmarked center loci of such projections or calipering theneighboring sides nf a recess and a projection spaced therefrom toindicate the distance between their unmarked center loci, which kinds ofwork are illustrated in Figs. 23 and 2li of the drawings in myco-pending application, Serial No. 28,368. led May 21, 1948.

Also as in my said co-pending application l may, by establishing asuitably modified relationship of beam stops 46 or G0 to the locationalong the beam of the range of the scale markings 35, or 55 on the beam,use instruments constructed and manipulated as herein to indicate as adirect reading on the instrument the true distance from a single knownlocus such as (n) to an unmarked locus such as (c) by spacing ofi orsuccessively calipering the distance (n-N) and (1L-F) In this case thecorrect initial register of the index mark on jaws l l or I0 should bezelo The correct initial register of the index mark on jaws 2l or 2Dshould be l/g and the correct initial register of the index mark on jaw53 should be lis" if a constant terminal of the other jaw be always usedto sense the known locus (n).

For conveniently shifting the initial register of the index mark, theshoulder 40 provided by head 39 may be constructed to be shiftable todifferent fixed stations along the beam, or the stop finger may be soconstructed. As an alternative there may properly be placed a pluralityof index marks on the seme jaw in addition to 29, 29' and 59 from all ofwhich marks there can be selected for each different job that index markWhose initial registration on the scale suits the Work whose dimensionsare to be measured and indicated according to the principles of thisinvention and as taught in my aforesaid copending application.

The appended claims are directed to and intended to cover all thevarious workable combinations and sequences of method steps taughtherein as well as obvious substitutes for the shapes and relationshipsof the structural elements of the instrument itself coming within thebroadcast fair interpretation of the claim language having referencethereto.

I claim:

l. A dimension lnding instrument aiTording direct reading of distancebetween unmarked work loci respectively'lying midway between one pair ofdiscernible work marks and midway between a, different pair ofdiscernible work marks, including in combination, a straight scale beam,a rst calipering jaw carrying in fixed relation thereto a referencepoint at a work sensing terminal portion of said jaw and slidablyengaged with said beam in a manner to be conned thereby to rectilinearmovement for measuring work, a second calipering jaw carrying in fixedrelation thereto a reference point at a work sensing terminal portion ofsaid secondY jaw and slidably engaged with sa-id beam in a manner to beconfined thereby to rectilinear movement relative to said beam into andaway from abutting engagement with said first jaw for measuring work,mutually registering relatively movable measurement indicators, one ofsaid indicators comprising an index movable in unison with one of saidjaws and the'other of said indicators comprising a scale of spaced apartgraduations carried by said beam ranging serially away from a beginninggraduation of said scale and denominated as dimensional values differentfrom but proportional to the true aggregates of spacings of saidgraduations from said beginning graduation, and a stop fixed on saidbeam in predetermined relation to said beginning graduation positionedto be engageable by one of said jaws in only one direction of slidingmovement of the latter thereby to limit mov-ement of both said jawsrelative to said beam in said direction and to permit free independentsliding movement of both said jaws relative to said beam and relative toeach other in the opposite direction. said stop being so located on saidbeam as to bring said index into register with said beginning graduationwhen said jaws are mutually engaged while said first jaw engages saidstop, and said beginning graduation being denominated as the truedimension of the distance that then intervenes between said respectivereference points.

2. A dimension finding instrument as defined in claim 1, in which one ofthe said jaws carries the said index, and the other of said jaws isslidably confined on the said beam between the first said jaw and thesaid stop.

3. A dimension finding instrument as defined in claim 1, in which one ofthe said jaws carries the said index and is slidably confined on thesaid beam between the other of said jaws and the said stop.

4. A dimension nding instrument as dened in claim 1, in which each ofthe said jaws presents two work sensing terminals separated by width ofthe said terminal portion of the jaw, and the said index is carried byone oi the said jaws in a position to register with that one of the saidgraduations in the said scale denominated a dimensional value equal toone half the combined said widths of said terminal portions of the jaws.

5. A dimension iinding instrument as dened in claim i in which each ofthe said jaws presents two work sensing terminals separated by width ofthe said terminal portion of the jaw. and the said index is carried byone of the said jaws in a position to register with that one of the saidgraduations in the said scale denominated a dimensional value equal toone half the sum of said widths of said terminal portions of the jaws,said index carrying jaw being slidably confined on the said beam betweenthe other of said jaws and the said stop.

6. A dimension finding instrument as defined in claim 1 in which eachoi' the said jaws presents two work sensing terminals separated by widthof the said terminal portion of the jaw, and the said index is carriedby one of the said jaws in a position to register with that one of thesaid graduations in the said scale denominated a dimensional value equalto one half the sum of said widths of said terminal portions of thejaws, the other of said jaws being slidably confined on the said beambetween said index carrying jaw and the said stop.

7. A dimension nding instrument as defined in claim 1, in which the saidbeginning graduation is denominated zero.

8. A dimension finding instrument as defined in claim 7, in which thesaid index is carried by the said one of said jaws which abuttinglyengages the said stop.

9. A dimension finding instrument as defined in claim 7, in which thesaid index is carried by one of said jaws, and the said stop isabuttingly engaged by the other of said jaws.

10. A dimension finding instrument as defined in claim 1, in which eachof the said jaws presents two work sensing terminals separated by widthof the said terminal portion of the jaw, and the said index is carriedby one of the said jaws in a position to register with that one of thesaid graduations in the said scale denominated a dimensional value equalto one half the sum of said widths of said terminal portions of the jawsplus the actual distance separating the nearest together of said worksensing terminals when one of the said jaws is in abutting engagementboth with the other of said jaws and with the said beam carried stop.

11. A dimension finding instrument as defined in claim 10, in which thesaid index is carried by the said one of said jaws which abuttinglyengages the said stop.

12. A dimension finding instrument as defined in claim 10, in which thesaid stop is abuttingly engaged by the one of the said jaws whichabuttingly engages the said index carrying jaw.

13. A dimension nnding instrument ailording direct reading of distancebetween unmarked work loci respectively lying midway between one pair ofdiscernible work marks and midway between a different pair ofdiscernible work marks, including in combination, a straight scale beam,a first calipering jaw carrying in fixed relation thereto the median ofwidth of at least one work sensing terminal of said first jaw andslidably engaged with said beam in a manner to be confined thereby torectilinear movement for measuring work, a second calipering jawcarrying in fixed relation thereto the median of width of at least onework sensing terminal of said second jaw and slidably engaged with saidbeam in a manner to be coni'lned thereby to rectilinear movementrelative to said beam into and away from abutting engagement with saidfirst jaw for measur ing work, mutually registering relatively movablemeasurement indicators, one of said indicators comprising an indexmovable in unison with one of said jaws and the other of said indicatorscomprising a scale of spaced apart graduations carried by said beamranging serially away from a beginning graduation of said Scale anddenominated as dimensional values diiferent from but proportional to thetrue aggregates of spacings of said graduations from said beginninggraduation, and a stop fixed on said beam in predetermined relation tosaid beginning graduation positioned to be engageable by one of saidjaws in only one direction of sliding movement of the latter thereby tolimit movement of both said jaws relative to said beam in said directionand to permit free independent sliding movement of both said jawsrelative to said beam and relative to each other in the oppositedirection, said stop being so located on said beam as to bring saidindex into register with said beginning graduation when said jaws aremutually engaged when said first jaw engages said stop, and saidbeginning graduation being denominated as the true dimension of thedistance that then intervenes between said medians of said work sensingtermi nais.

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